Sanding machine



Feb. 10, 1942. L, E, ARKER 2,272,273

SANDING MACHINE Filed Jan. 5, 1940 2 Sheets-Sheet 1 l'l I INVENTOR. 70 J2 47 I ATTORNEYS.

Feb. 10, 1942. PARKER 2,272,273

SANDING MACHINE Filed Jan. 5, 1940 2 Sheets-Sheet 2 lllllllllll lulm INVENTOR EParfler ATTORNEYS.

Patented Feb. 10, 1942 UNITED STATES PATENT OFFICE SANDING MACHINE Leonard E. Parker, Cary, 11]., assignor to Skilsaw, Inc., Chicago, 111., a corporation of Delaware Application January :1940, Serial No. 312,454,

(Cl. 51-170) I chine constructed in' accordance with the pres- 3 Claims.

This invention relates to wood-working machines of the portable type, and more particularly is concerned with machines for sanding Purposes.

The main and primary object of the invention is to provide a machine of the character referred to having novel and emcient means for tensioning the sanding belt and removing the tension therefrom when such is required. A machine so constructed permits ready access to the sandpaper for replacement of the same when it has become worn and incapable of further use, and the sandpaper likewise is subjected to the required degree of tension to render it capable of serving its purpose to the highest degree.

A furthefobject of the invention is the provision of simple and efllcient means for freeing the sandpaper belt of the tension to which it is sub- Jected, and'thus enabling easy replacing of the sandpaper when such is required. Furthermore, the invention seeks to provide a ent invention;

Fig. 2 is a fragmentary sectional plan view on the line 2-2, Fig. '1, the front supporting roll and its adjusting means being illustrated as when the roll is distended;

Fig. 3 is a view similar to Fig. 2, the movable parts occupying the positionwhich they assume when retracted;

Fig. 4 is a longitudinal sectional view as on the line l--4, Fig. 2, the parts being illustrated on an enlarged scale:

Fig. 5 is a central longitudinal sectional view of the herein described machine taken through. the motor chamber and illustrating the connecting gearing between the motor and the driving roll, the position of the sanding machine being reversed to that illustrated in Figs. 1 to 4, inelusive;

Fig. 6 is a vertical transverse sectional view as on the line 6-6, Fig. 5.

by another belt, with the expenditure of but a minimum amount of time in making the replacement.

The invention'also has in contemplation the provision of a sandpapering machine designed and adapted for maintaining proper feed and travel of the sandpaper belt. In the event the action of the belt becomes impaired the invention also includes means for restoring the same to proper operating condition-so that the belt becomes freed from its impairment, and its proper subsequent operation is insured.

Having these and other objects of like import in view, the invention consists substantially in the novel construction, combination and arrangement of parts hereinafter fully described, illustrated in theaccompanying drawings, and finally pointed out in the appended claims.

While the form of the invention herein shown and described is believed to be a preferred embodiment thereof, it is to be understood that the same is susceptible to changes in the form, proportion andminor details of construction, and the right is, therefore, reserved to resort to such changes without departing from the spirit or scope of the invention.

= In the drawings Referring in detail to the accompanying drawings, the numeral l0 designates the sustaining deck of the herein described sander which constitutes the support for the operative parts of the machine: as well as the casing which houses the driving motor and the gearing for transmitting The rear end of the sustaining deck "I has a transverse depending curved guard I lthe lower edge of which terminates above the surface on which the sander rests, as clearly seen in Fig. 1, and thus the rear end is free from contact with such surface.

Arranged above the sustaining deck l0, and

disposed in inclined relation thereto, is a motor casing lb of generally cylindrical form, which casing extends longitudinally of the deck l0. Within the casing ISis located an electric motor l6 of any'suitable construction and type adapted for the purposes of the present machine, the armature shaft ll of said motor being sustained by and operating in front and rear ball bearings I Wand l9 respectively. The front bearing II is positioned within a supporting head 20 that may Fig. 1' is a side elevation of a sanding mabe detachably connected to the casing I5, and

said head 20 has a plurality of longitudinallyextending slots 2| formed therein for the admission and circulation of air for cooling the motor IS. The rear bearing l9 receives the rear end of the armature shaft 11 and sustains the latter in proper operative position.

At the rear end of the casing the latter is provided with a series of openings 22 for the entrance of air that may be entrained within the casing by a suitable fan 23 carried by the armature shaft l1 and interposed between the armature and the rear ball bearing IS. The motor verse arcuate slot 43 in which a fastening screw 43 is loosely received, the screw 43 being enaged with the end of the guide block 43 that is most remote from the point of engagement of the pivotal screw 41 with the guide block. By reason of this slotted engagement, the screw 43 serves to guide the lateral swinging movement of the guide bloclr', and to maintain the latcasing i5 has a grated opening 24 that surrounds the fan 23, said opening being provided with covering plates 25 that extend over the upper portion of the opening 24 and by which the latter is partially closed to protect the fan against damage by the admission of extraneous substances other than the air.

The front ball bearing I8 is in communication with a lubricant chamber 26 that is closed by a removable screw plug 21.

Within the rear end of the motor casing l5, and extending transversely thereof, a gear chamber 28 is formed, a worm gearing 29 being located therein and affording driving connection between the armature shaft ll of the motor i6 and a transverse shaft 30. This shaft is' mounted in spaced ball bearings 3| fitted within the gear chamber 28, and said shaft 30 is provided with a pinion 32 that is fitted to the projecting end of that shaft. This pinion 32 is located within a gear housing 33 which is arranged at the rear side of the motor casing I5 and projects at that side. A driving chain 34 is associated with the pinion 32, which chain also traverses a pinion 35, preferably of greater diameter than the pinion 32, which pinion 35 is mounted on the shaft 38 of a driving roll 31. The shaft 33 passes through the vertical supporting plate and said driving roll 31 is fastened to the shaft 36 in any desired manner in order that the roll may operate with said shaft.

The gear housing 33 has a cover plate 38, and this is detachably secured to the housing through the medium of a series of fastening screws 39.

That the driving chain 34 may be properly ten sioned in its operation a spring-actuated contact finger 40 is mounted within the housing 33 and yieldingly bears against one stretch of the chain 34, as clearly illustrated in Fig. 5.

The driving roll 31 fits beneath the supporting deck I!) in proximity to the guard |4 thereof, and said roll is actuated from the motor i6 through the medium of the worm gearing 29 and the chain 34 that is engaged with the pinions 32 and 35. Preferably, the driving roll 31 is formed of rubber so as to have a tenacious engagement with an endless sandpaper belt 4|, which belt operates over the driving roll 31 and also a supporting roll 42 that is journalled in a U-shaped supporting fork 43. This fork 43 has a. rearwardly-extending cylindrical guide stem 44 that is received by an elongated cylindrical bore 45 formed within a guide block 46. The guide block 46 is mounted upon the supportingshoe i2, being held for pivoted movement on said shoe by a fastening screw 41. This permits the guide block 46 to be swung laterally with respect to the shoe l2, as occasion may require, in order to determine the proper engagement of the supporting roll 42 with the sandpaper belt 4|, and thus maintain proper alignment of the roll and the sandpaper.

The shoe i2 is also provided with a transter in proper horizontal position on the shoe l2.

Within the cylindrical bore 45 is located a coil spring 50 which seats against the closed end of said bore. The opposite end of said spring 50 is designed to contact the end of the guide stem and, when this stem is forced outwardly, a stop II, which is in the form of a transverse pin spanning the cylindrical bore 45, horizontally thereof and having its ends fixed in the guide block. The pin II is received by a slot 52 that is formed transversely of the inner end of the guide stem 44. By reason of the pin 5| fitting within the slot 52 as indicated, the pin 5| holds the guide stem 44 against rotation, and maintains the supporting roll 42 also against horizontal deflection so as to prevent deflection of the endless belt 4|.

The guide block 43, at its upper side, has an elongated slot 53 formed therein. This slot receives a fastening screw 54 that is detachably engaged with the guide stem 44. the screw 54 being capable of free sliding movement lengthwise or the slot 53. The screw 54 is carried by an actuating lever 55 which may freely swing upon said screw 54. Also pivotally connected to one end of the lever 55 is a link 50. a headed stud 51 serving to connect the link I and the lever 55. 'Ihelinlrlialsoisconnectedtoafastening screw 53 which is threaded into the guide block 46 at the end thereof adjacent to the fork 43.

Through the medium of the actuating lever 55 forward and backward movement of the supporting roll 42 may be effected in order to apply tension on the belt 4| and to release the belt from such tension. Thus, in the position of the parts illustrated in Fig. 2, tension of the spring 50 is exerted against the guide stem 44 to force the same outwardly, and thereby to tension the sandpaper belt 4| As the parts are illustrated in Fig. 3, however, the spring II is compressed, and the fork 43 with its guide stem 44 is retracted so that the belt 4| is not under tension. In such position the belt 4| readily may be removed from the rolls 3'! and 42, either for replacement by a new belt, or for such other purposes as may render desirable such removal.

With the parts positioned as in Fig. 2, the relative straightening of the actuating lever 55 and the link 56 causes the fastening screw 54 to move along the slot 53 against the pressure of the spring 50 exerted against the guide stem 44. This retracts the supporting roll 42 and loosens the belt 4|, as indicated. It will be noted, however, from Fig. 3 that in the position of the actuating lever 55 and the link 53 the screw 51 has been swung slightly beyond the dead center point so that thelever 55 and the link 55 are not in direct alignment. This looks these parts against further movement, and this position is maintained by an upstanding contact finger 53 carried by the actuating lever 55 and designed to engage the edge of the link 56, asillustrated in Fig. 3. This precludes reverse movement of the lever 55 until sufilcient pressure has been applied thereto to swing the contact finger 59 backwardly away from the link 56. y

For the purpose of swinging the guide block v 2,272,378 46 on the pivotal screw 41, and thus .to cause the Y roll 42 squarely to engage the sandpaper belt 4|,

the guide block 46 is provided with a pair of spaced ears 66, and pivotally connected between said ears 66, as at 6|, is a guide shank 62. This is provided with a screw-threaded extremity 66 on which is mounted an adjusting nut 64 that bearsagainst the outside of the vertical supporting plate I the shank 62 passing loosely through the supporting plate Interposed between the latter and the ears 60, and surrounding the shank 62, is a coil spring 66 which offers resistance tothe action of the adjusting nut 64 when the latter is tightened. The movement, therefore, of the guide block 46 is cushioned by the spring 65, and the latter imparts elastic resistance to the movestood that upon the actuationof the switch 14.

operation of the motor l4. These elementsform no part of the present invention and require no further description as to their form and construction. v

With the parts described as above, and as-' sembled in the manner shown, it will be underthe cable 14 being connected to a suitable source ment of the guide block 'when the nut 64 is tightened. As above indicated, the engagement of the stop pin 6| with the slot 62 holds the shank 44 against rotation, and maintains the proper presentation of the supporting roll 42 to the sandpaper belt 4|. Proper feed and travel of the. sandpaper belt 4 I therefore, can be maintained. Should a square contact of the face .of the supporting roll 42 with the belt 4| be not had, rotation of the nut 64 in either direction will cause movement of the guide shank 62 inwardly or outwardly, with a correspondingly swinging of the roll 42 in either direction. Thus, a square engagement of the face of the roll 62 with the belt 4| may be had, thereby insuring proper feed and travel of the sandpaper belt 4 I, and preventing its deflection towards either end of the roll 42 as the sandpaper passes over the roll.

To insure the proper distention of the lower reach of the sandpaper belt 4| towards the surface being treated, a pressure plate 66 is arranged next adjacent to and in contact with such lower reach. The forward end of the shoe I2 is deflected upwardly, as more clearly shown in Fig. 4, toprovide an anchoring lip 61 the forward end of the pressure plate 66 likewise being deflected upwardly and secured to said lip 61 by means of a clamping strip 68 and a plurality of holding screws 69 that pass through the strip 68 and en- 'gage the lip 61. Interposed between the pressure plate 66 and the shoe l2, with. itsforward end held to the lip 61 by the plate 66, the clamping strip 66 and the screws 69, is a cushion pad 10 that may be formed of cork or similar material.

' -over the plate 66 and thepad 10 such springing action will tension the lower reach of the'belt 4|. This will distend such lower reach of the of electrical energy, the motor l6 will be set in operation. Through the'worm gearing 29, the

shaft 26, and the interposed gearing 32, 34 and 66, motion will be transmitted to the driving roll 21. The sandpaper belt 4| being trained around positioned as shown in Fig.2, the roll 42 will be projected forwardly or outwardly and the sandpaper belt 4| thereby placed under tension. This 4 is the operative position of the machine. As it continues, the presentation of the sandpaper belt 4|, being urged outwardly by the pressure plate 66 and the pad 16 to the surface being treated, will cause the surface to be cut away and smoothed, and this will continue so long as the machine is in operation. It is assumed that in this operation the supporting roll 42 is adjusted to present its surface squarely to'the sandpaper belt 4| and thereby present the latter in the same manner-to the work. If, however, a deflection of the roll 42 has arisen so that the surface thereof is. presented at an angle to the face of the work instead of a square presentation of 'such surface, such condition may be met and easily remedied by proper manipulation of the nut 64 to swing the guide block 46 either forwardly or backwardly on its pivot 41.

- Should it be desired to remove or replace the sandpaper belt 4| the actuating lever 55 and the link 66 are positioned as illustrated him. 3. when so positioned the guide stem 44 is retracted against the pressure of the spring 50 and the supporting roll 42 thereby moved towards the guide block 46.- The sandpaper belt 4| thus becomes slack and mav be removed freely from the rolls 3'! and 42. When soremoved a further belt may be substituted for the one displacedi Thereupon, the actuating lever and the link 56 are positioned as illustrated in Fig. 2, with a resultant tensioning of the belt for further outting. I

' It will be observed that in the movement of the roll 42 the anchorage of the link 56 to the fixed fastening screw 66 effects the longitudinal movement of the fastening screw 54 and the connected guide stem 44.- The latter, therefore, moves belt 4| and maintain the same taut so as properly to engage the surface that is to be smoothed by the sandpaper.

For the convenient manipulation of the herein described sander the latter is provided with a handle loop suitably connected at its upper end to the motor casing l5 and at its lower end to the transverse curved guard l4. A handle knob 12 is detachably connected to the forward end of the motor casing IS. a

A suitable cable 13, containing the requisite conductors for supplying the motor IS with the necessary electrical energy for its operation, enters the handle loop 1|, being connected to a switch 14 of approved design for controlling the backwardly and forwardly according to the straightening or breaking of the alignment of the actuating lever 65 and the link 56.

I. claim:

1. In a'san'ding machine, the combination with a sustaining frame, a driving roll carried thereby, and means for operating said driving roll, of a supporting roll associated with said sustaining frame and movable relatively to said driving'roll, an endless abrasive belt trained over said rolls, means for moving the. supporting roll in relation to the driving roll to maintain the abrasive belt in distended position, and manually operable toggle mechanism, for retracting the supporting roll to a fixed position to loosen the abrasive belt and free the-latterfrom its distended position.

2. In a sanding machine, the combination with a sustaining 1rame, a driving roll carried thereby and arranged at one end thereof, and means for operating said driving roll, oi a supporting roll associated with said sustainingirame and disposed at its opposite end, said supporting roll being movable relatively to said driving roll, an endless abrasive belt trained over said rolls, means arranged between said driving and supporting rolls and operatively related to the supporting roll to maintain the abrasive belt in distended position, and means including a toggle joint for retracting the supporting 'roll and locking it in retracted position to loosen the abrasive belt and tree the latter from its distended position.

3. In a sanding machine, the combination with a sustaining frame, a driving roll carried thereby,

ment serving to lock the supporting roll against outward movement. whereby to release said end- 45 less abrasive belt from tension.

LEONARD E. PARKER. 

